Ask question

Ask question

All categories

2 years ago

14

Plug variables expressed in SI units in the kinematic equation given in article: a = -v0^2/(2sg). What value of g you get as exp

ressed in g's where g = 9.8 m/s^2 1 point the same as in English units smaller larger this calculation cannot be performed in SI units If the initial velocity of player is doubled then the absolute acceleration would * 1 point decrease 2x stays the same increase 2x increase 4x If stopping distance is decreased 2x then the acceleration would * 1 point decrease 2x stay the same increase 2x increase 4x Other: Hockey player having initial velocity 20 m/s and helmet having padding 5 cm hits head on his twin brother. The acceleration of his brain is most closely equal to * 1 point 0.4g 4g 40g 400g

1 answer:

Elanso [62]2 years ago

6 0

Answer:

1) acceleration is increased by a factor of four 4X

2) the acceleration increases a factor of 2X

3) the correct answer of 400g

Explanation:

This is a kinematics exercise, where you use the velocity equation to obtain the acceleration, with the final velocity equal to zero.

v² = v₀² + 2 a x

0 = v₀² + 2 a x

a = - v₀² / 2 x

In the case of wanting to give the acceleration as a function of g, we can find the relationship between the two quantities

a / g = - v₀² / (2 x g)

Let's answer the different questions about this equation

1. The initial velocity is doubled, how much the acceleration is worth

a/g = - (2v₀) 2 / 2xg

a = 4 (-v₀² / 2xg) g

acceleration is increased by a factor of four 4X

2. if the stopping distance is reduced by 2, that is, x = x₀ / 2

we substitute

a/g = (- v₀² / 2g) 2/x

a =2 (-v₀² / 2x₀g) g

therefore the acceleration increases a factor of 2X

3. the initial velocity of the hockey player is v₀ = 20 m / s and the stopping distance is

x = 5cm = 0.05m

we calculate the acceleration

a / g = - 20² / (2 0.05)

a / g = - 4000 / g

a / g = - 4000 / 9.8 = 408

a = 408 g

the correct answer of 400g, the value matches exactly if g = 10 m / s2 is taken

You might be interested in

Two planes leave wichita at noon. one plane flies east 30 mi/h faster than the other plane, which is flying west. at what time w

scoundrel [369]

You have to take note of the individual directions of the plane. Since one is heading east, and the other is heading west, the planes are heading at opposite directions. So, it means that their distance between each other would be equal to 1,200 miles which accounts for the sum of their individual distances. The equation is as follows:

Total Distance = Distance of slower plane + Distance of faster plane
1,200 miles = st + (30+s)(t)
where
s is the speed of the slower plane and t is the time. Since both are not given, the final answer would just be in terms of s.
1,200 = t(s + 30 + s)
t = 1200/(30+2s)
t = 600/(15+s)

4 0

2 years ago

Liam throws a water balloon horizontally at 8.2 m/s out of a window 18 m from the ground.

Alecsey [184]

Time taken by the water balloon to reach the bottom will be given as

$h = \frac{1}{2} gt^2$

here we know that

$h = 18 m$

$g = 9.8 m/s^2$

now by the above formula

$18 = \frac{1}{2}*9.8* t^2$

$18 = 4.9 t^2$

$t = 1.92 s$

now in the same time interval we can say the distance moved by it will be

$d = v_x * t$

$d = 8.2 * 1.92 = 15.7 m$

so it will fall at a distance 15.7 m from its initial position

5 0

2 years ago

A convex mirror with a focal length of 0.25 m forms a 0.080 m tall image of an automobile at a distance of 0.24 m behind the mir

Semmy [17]

Answer:

The distance and height of the object is 6 m and 2 m.

The image is virtual and upright.

Explanation:

Given that,

Focal length = 0.25 m

Length of image = 0.080 m

Image distance = 0.24 m

We need to calculate the distance of the object

Using formula of lens

$\dfrac{1}{v}=\dfrac{1}{f}+\dfrac{1}{u}$

Put the value into the formula

$\dfrac{1}{0.24}=\dfrac{1}{0.25}+\dfrac{1}{u}$

$\dfrac{1}{u}=\dfrac{1}{0.24}-\dfrac{1}{0.25}$

$\dfrac{1}{u}=\dfrac{1}{6}$

$u=6\ m$

We need to calculate the magnification

Using formula of magnification

$m=-\dfrac{v}{u}$

Put the value into the formula

$m=-\dfrac{0.24}{-6}$

$m=0.04$

We need to calculate the height of the object

Using formula of magnification

$m=\dfrac{h'}{h}$

$h=\dfrac{0.080}{0.04}$

$h=2\ m$

A convex mirror produce a virtual and upright image behind the mirror.

Hence, The distance and height of the object is 6 m and 2 m.

The image is virtual and upright.

6 0

2 years ago

Read 2 more answers

An electron and a proton, starting from rest, are accelerated through an electric potential difference of the same magnitude. in

Yakvenalex [24]

The charges are the same in absolute value, so the change of potential energy is the same. That means that the change in kinetic energy is also the same. Then:

1 = Ke/Kp = m_e *v_e^2 / m_p * v_p^2, or

v_e/v_p = sqrt( m_p/m_e),

So the speed of the electron will be sqrt( m_p/m_e) times greater than the speed of the proton

4 0

2 years ago

A piece of copper of mass 100 g is being drilled through with a 1/2" electric drill. The drill operates at 40.0 W and takes 30.0

lesantik [10]

Answer:

correct option is c. 31.0°C

Explanation:

given data

copper of mass = 100 g

electric drill = 1/2"

power = 40.0 W

time = 30 s

C copper = 387 J/kgC

to find out

copper's increase in temperature

solution

we get here energy that is express a s

energy = 40 W × 30 s

energy = 1200 Watt seconds

and heat acquired by drill is here as

heat acquired = 100 × T × 387

here temperature rise in copper mass as

temperature rise in copper mass = $\frac{100}{1000}$ × T × 387

temperature rise in copper mass = 38.7 × T Watt second

we know that all the energy from the drill heats the copper

so we can say

38.7 × T = 1200

T = 31°C

so correct option is c. 31.0°C

4 0

2 years ago